In the manufacture of integrated circuits (ICs), devices are formed on a wafer by forming various process layers, then selectively removing or patterning portions of those layers and depositing additional process layers thereon. After deposition steps, an uppermost surface of the wafer is usually non-planar because of previous selective patterning. A planarization process is performed in succession to remove excess portions and prepare a flat surface for the following process.
A chemical-mechanical polishing process (CMP process) is utilized for the planarization process. The wafer to be processed is held upside down and forced against a rotating CMP pad. A slurry is disposed between the CMP pad and wafer surface. Due to the applied down force, this slurry, which includes chemicals that help chemically dissolve the uppermost surface of the wafer and abrasive particles that help physically wear away the uppermost surface, provides for wafer surface planarization.